Turbodiesel Battlefield

It was curious placement for two rival automotive suppliers at this month's Frankfurt Motor Show.

Standing in adjoining booths on the second level of Hall 5 were two parts makers that have staked out turf in Europe's bustling market for diesel fuel injectors: Siemens VDO Automotive Corp. and Delphi Corp.

Siemens was the first three years ago to incorporate quick-firing piezo (pronounced pee-AY-tso) actuators in diesel injectors, and the other major players have said they will follow the same technological path, including Robert Bosch GmbH, Denso Corp. and Delphi.

Piezo actuators are incredibly quick, injecting fuel into the cylinder in less than ten thousandths of a second — up to six times faster than conventional solenoid valves.

That speed translates into more precise shaping of the air-fuel mixture, which means quieter, more fuel-efficient, cleaner and more powerful diesel engines.

But at its Frankfurt press conference, Delphi suggests piezo actuators will not necessarily replace the conventional solenoid valves that have sustained diesel fuel injectors for years.

Volker Barth, president of Delphi Europe, Middle East and Africa, calls piezo an “important advancement” and admits his company will produce its first piezo injectors in Europe around 2006. He says Delphi's Piezotec actuators will improve emissions by up to 30% when compared to today's “best piezo common-rail technologies.”

But Barth says Delphi has managed to exceed Euro 4 emissions requirements without piezo actuators and further expects to meet the more stringent Euro 5 regulations by optimizing its solenoid-based Multec fuel injectors. He says the next-generation Multec system will be ready for market next year.

Barth tells Ward's that piezo injectors are at least twice as expensive as solenoids, and that auto makers developing new engines may struggle to justify the added expense for piezo.

Echoing comments from Denso officials at last spring's Society of Automotive Engineers World Congress in Detroit, Barth says some auto makers are interested in “piezo” because the moniker has a high-tech ring to it.

“If a customer would like to have piezo just to be able to say, ‘I have piezo technology,’ then what we offer to our customers is a choice. Because solenoid is still much cheaper than piezo, and the cost is very important,” Barth says.

“For some customers, cost may be less important than image, so they might decide for piezo,” he adds, “even if they could have a solenoid solution.”

He remains “very confident” that Delphi will continue producing solenoid-based diesel injectors for many years to come.

“I'm definite because the auto industry doesn't have the luxury, except for some niche products, to go for a higher-cost solution when it's not required.”

Siemens VDO disagrees with Barth's price comparison. The supplier says its piezo injectors have won at least seven new contracts (rolling out in Europe over the next three years), and that the competition for each of those contracts was conventional solenoid systems.

Delphi has produced more than 2 million common-rail diesel systems since acquiring the Europe-based Lucas Diesel Systems from TRW Inc. in 1999, and the world's No.1 supplier is adding capacity to manufacture about 2.5 million systems per year by 2007.

Down the hall at Frankfurt was Denso, where the message about diesel was surprisingly similar. The company says it, like Delphi, will continue developing both solenoid and piezo actuators for its fuel injectors.

Denso claims to have the world's most-advanced solenoid actuators, achieving injection pressures of 1,800 bar (26,106 psi) and five injection events per intake cycle. Its first customer for the solenoid-based system is Ford of Europe; the contract is worth E100 million ($111 million) a year, beginning in 2005.

Still, for those customers that want it, Denso will produce its first piezo injectors in Hungary, also in 2005.

Likewise, Bosch, the world's No.1 supplier of diesel fuel injectors, says it has five or six European customers for the piezo injectors it will produce within the next two years.

The new piezo actuators will appear on Bosch's third-generation common-rail system, which debuts on Audi AG's new 3L V-6 TDI that is optional on the A8 flagship.

Bosch says the piezo technology translates into a 20% improvement in emissions for the Audi engine when compared to “the best previous” solenoid and piezo systems available.

The Audi system achieves injection pressures of 1,600 bar (23,206 psi) — 250 bar (3,625 psi) higher than earlier common-rail systems. By way of visual assistance, Audi says 1,600 bar is the equivalent of a midsize car pressing down on the area of a fingernail.

Meanwhile, Bosch has said recently its unit-injector system for Volkswagen AG can achieve even higher pressures of 2,050 bar (29,732 psi) with conventional solenoids. Still, VW wants lightning-fast piezo injectors and has a joint venture with Siemens VDO to produce them, beginning late next year.

Siemens VDO finds its competitors' public ambivalence toward piezo actuators to be disingenuous, given that all of them are developing fuel injectors that take full advantage of the technology. Siemens VDO has produced more than 2 million piezo fuel injectors since 2000.

The German supplier remains so committed to piezo that it now wants to apply the technology to direct-injection gasoline engines.

In a gas engine, the piezo actuator would be integrated into the injection valve. When the piezo element receives an electrical impulse, the nozzle needle opens the injection valve and the fuel is metered far more precisely than with a solenoid valve. Siemens VDO projects a 20% fuel consumption improvement with the gasoline piezo system.

Siemens VDO CEO Wolfgang Dehen says piezo has a bright future among the ever-changing automotive powertrain landscape.

“We were first to market with piezo technology. We believe in that technology,” Dehen says, seizing the opportunity to take a jab at his biggest competitor: Bosch — Germany's largest supplier — whose headquarters is just outside Stuttgart.

“By the way, people in the Stuttgart area also now believe in that technology,” Dehen says. “I think we are progressing according to our long-term strategic roadmap.”